The training goal of this career development grant is to become an independent scientific investigator contributing to the understanding of the social processes through which gay and bisexual male adolescents and emerging adults (GBMAEA) develop a range of health disparities, including HIV/AIDS, depression, and substance use. These processes require investigation in order to inform the development of multilevel and structural interventions to eliminate these disparities. In order to achieve these goals, I propose to develop and apply skills in the areas of adolescent development, psychosocial scale development and validation, latent class analysis and mixed models. Dr. Gary Harper will oversee my professional development under this proposal. In addition to supervising my progress through the proposed research and training plan, Dr. Harper will supervise my training in two areas of skill development: qualitative data analysis methods and adolescent development theories and applications. Dr. Isa Fernandez will act as a co-mentor and senior methodologist working with me on secondary data analysis, sampling and recruitment methods and supervision of my grantsmanship and R01 proposal development. Dr. Richard Campbell will act as a co-mentor and supervise my training in statistical methods, including psychosocial scale validation, item response analysis, latent class analysis, and mixed models. Dr. Ron Stall will act as a co- mentor and supervise my training in developing and testing a model of syndemic production of HIV/AIDS and health disparities. The goal of the proposed research is to empirically test a model of syndemic production of negative health outcomes among GBMAEA, and to investigate possible resiliencies among this population that are associated with positive health outcomes. I will assess (a) how these male adolescents and emerging adults perceive, experience and internalize gay-related stigma, (b) how sexual identity development is correlated with the perception, experience, and internalization of gay-related stigma, (c) to what degree these stigma processes and sexual identity development are associated to a range of health risk indicators, and (d) to what degree perceived social support moderates the effects of stigma and sexual identity development on health behaviors. This application supports the mission of the National Institute of Mental Health by producing data on sexual identity development trajectories, gay-related stigma, and health behaviors of GBMAEA that will help inform the development of theoretically sound multi-level and structural interventions in the future to address HIV/AIDS and health disparities among this population.